I have a Macbook Air 13" and bootcamp into Windows 8. In order to get 2 displays off the thunderbolt port, I connect my monitors using a Matrox Triplehead2Go DP edition. When I got new monitors the other day so I can have a larger resolution (needed 1920X1080 instead of 1680X1050 per monitor) i started noticing something weird on the start screen. In the old resolution (3360X1050 = 2*1680X1050) the start screen tiles were normal sized and stacked 5 high. When I put the new monitors in, and set the resolution to 3840X1080 the tiles got really large and stacked only 3 high. At the new resolution all metro type menus seem to be extremely large.
I tried different monitors and got the same result. I also went into the PC Settings (the new metro control panel) and went to the "Ease of Access" screen and then tried to toggle the "Make everything on your screen bigger" option but it is grey'd out and there is a message "Your display doesn't support this setting" beneath it.
Here are screen shots:
3360X1050 = 2*1680X1050: here
3840X1080 = 2*1920X1080: here